How Do I Build a Soy-Wax Procurement System That Determines Pack Size, Reorder Point, Safety Stock and Bulk-Purchase Quantity from Actual Monthly Consumption?

Six inputs, five calculations, four numbers — recalculated on the first of every month

Every post in this cluster answers one buying question: whether a 100 kg minimum is justified, whether a saving is meaningful, whether to preserve cash, when to reorder, how much buffer to hold, how to plan a festival, how to release lots, how to document scale, when to start treating wax as inventory. A system is what you get when you answer all of them from the same data, in the same order, on the same day each month — so that nobody has to remember the reasoning, only follow the sheet.

The system needs six inputs you measure yourself: consumption history (six to twelve months of kilos used); real lead time (supplier days plus your own ordering and checking days); listed packs and prices for your approved wax; a service level; an order cost and holding rate; and a holding horizon. It runs five calculations — forecast, safety stock, reorder point, order quantity, bulk cap — and produces four numbers that run your purchasing: the pack size you buy, the reorder point, the safety stock and the order quantity, with a ceiling on any bulk offer.

In the worked example — a maker using CSI 464 whose last six months ran Apr 42 kg, May 48 kg, Jun 45 kg, Jul 55 kg, Aug 51 kg, Sep 60 kg — the answers are: buy 10 kg bags; reorder at 22.6 kg; hold 6.0 kg of safety stock; order 80 kg at a time, about 8.3 times a year; and refuse any bulk offer above 166 kg however good the price. Every example figure is labelled; the sheet below is built so you can replace them.

The copyable procurement sheet

Copy this table into a notebook or spreadsheet. The "Your number" column is for your figures; the example column shows the worked case. The formulas are standard inventory arithmetic — nothing in them is specific to CSI or to soy wax.

Step one: choose the pack size from the listed per-kg prices

Pack size is the first answer because it sets the unit of everything else — the reorder bin, the order quantity, the lot label. The rule is simple: find the lowest price per kilo among the listed, in-stock packs of your approved wax; if two packs are within about half a percent of each other, choose by handling (the unit you open at one time, and the unit you can rotate first-in-first-out). Here is the rule applied to CSI's four container soy waxes.

The table is a useful reality check before any bulk decision. Only Natural Soy Pearl has a real pack-size step (5.6% at 5 kg); CSI 464 is flat; CSI 468 drops ₹13.00 a kilo at 10 kg; and Luxury Soy Wax Chunks are cheapest per kilo in the 500 g bag and fractionally dearest in the 10 kg bag. On CSI's listed catalogue, pack size mostly buys convenience, not a lower rate. The 100 kg MOQ threshold and the ₹40-per-kg payback count explain how to judge an offer that does carry a discount.

Steps two to five: the worked calculation

Forecast. The example uses the average of the last three months, 55.3 kg, because use has been rising gently. A maker growing fast should use a trend instead, and one with a strong festive season should forecast by season — the growth case and the seasonal case show both. Safety stock. With σ = 6.6 kg across the six months, a 95% service level and a 9-day real lead time: 1.645 × 6.62 ÷ √30 × √9 = 6.0 kg. Reorder point. 1.84 × 9 + 6.0 = 22.6 kg, kept as 3 sealed 10 kg bags on a REORDER shelf.

Order quantity. The economic order quantity balances the cost of placing orders against the cost of holding stock. With annual use of 664 kg, an example order cost of ₹400.00 and a holding cost of ₹91.33 per kilo per year (₹507.40 × an example 18%), √(2 × 664 × 400 ÷ 91.33) = 76.3 kg, rounded to 80 kg. That is about 8.3 orders a year, one every 43 days, with an average stock of 46.0 kg. The total of ordering and holding costs is flat near the optimum, so rounding to whole bags costs almost nothing. Bulk cap. 3 months × 55.3 kg = 166 kg: the largest single purchase the system will accept, whatever the discount.

Notice the shape: tiny orders waste money on ordering, huge ones on holding, and the bottom of the curve is wide. That is why the system's order quantity is a range you can round into, and why a large bulk order needs a genuine discount — not just a sense that "buying big is cheaper" — to beat it.

How the system judges a bulk offer

Suppose a supplier offers 200 kg at ₹480.00 a kilo — an example quote, ₹27.40 below the CSI 464 rate. The system asks three questions in order. Cap: 200 kg is 3.6 months of use, above the 166 kg cap — so the answer is "negotiate down to the cap, or decline". Cash: if the cap were met, the saving (₹5,480.00 on 200 kg) would be compared with the carrying cost (₹2,602.41 on the half-lot method at 1.5% a month). Quality: if the offer is a different wax or supplier, it goes to the 4 + 4 test before anything else. Cash now versus unit cost covers the cash question in full.

The gate: no new wax enters the system without a 4 + 4 test

The sheet invites one tempting shortcut. Natural Soy Pearl is the only CSI soy wax with a pack-size step, and at its ₹424.80 rate a 200 g Mango Coconut candle costs ₹218.29 in materials against ₹233.49 in CSI 464 (10 kg rates, wick and jar included; labour, packaging, freight and GST excluded). That is ₹15.20 a candle, about ₹4,352.89 a month at this maker's volume. But that is a wax change, not a procurement decision, and the system must not make it by itself.

The gate is the standard control comparison: four candles in the approved wax as the control, four in the candidate, same oil lot, wick, jar and pour day; three burned, one shelved. These counts are a labelled working practice. CSI's product page for CSI 464 states up to 10% fragrance load and an 80–90°C melt/pour working range; Natural Soy Pearl's page publishes no melt point, pour temperature or fragrance ceiling. Those differences do not tell you which suits your candle. The sheet does.

If it passes, the kit pays for itself in about 129 candles. If it fails on any safety line, the ₹15.20 a candle was never available to you, and the system has done its job by refusing to buy it.

The monthly routine that keeps the system honest

For the maker in this example on 1 October 2026, the system says: keep buying Luxury Soy Wax CSI 464 in 10 kg bags; set the REORDER bin at 3 bags (30 kg); when it is opened, order 80 kg — 8 × 10 kg for ₹40,592.00; hold 6.0 kg as safety stock; decline any single purchase above 166 kg; and run the ₹1,967.00 gate test on Natural Soy Pearl this month if the ₹15.20-a-candle saving interests you. Because Diwali falls on 8 November, switch line B to the festive forecast today — the Diwali plan shows how.

The whole cluster, mapped to the sheet

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